U.S. patent application number 15/316564 was filed with the patent office on 2017-06-29 for rectangular wire stator coil manufacturing method.
This patent application is currently assigned to NISSAN MOTOR CO., LTD.. The applicant listed for this patent is NISSAN MOTOR CO., LTD.. Invention is credited to Koji HIGAKI, Kunitomo ISHIGURO, Yasushi MATSUSHITA, Kimio NISHIMURA, Takumi OHSHIMA, Masahiro OMATA, Takashi SEKIKAWA, Hiroaki SHIBUKAWA, Min WU, Yuhei YAMENE.
Application Number | 20170187271 15/316564 |
Document ID | / |
Family ID | 54833037 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170187271 |
Kind Code |
A1 |
SEKIKAWA; Takashi ; et
al. |
June 29, 2017 |
RECTANGULAR WIRE STATOR COIL MANUFACTURING METHOD
Abstract
A rectangular wire is wound on a stator core having a plurality
of teeth and a plurality of slots. A plurality of rectangular wire
elements is provided by cutting a rectangular wire into a
predetermined length and bending into a substantial U-shape. A
plurality of rectangular wire pieces configured to form a coil by
connecting predetermined end portions of the rectangular wire
elements is molded as a sub-assembly. Each of the plurality of the
rectangular wire elements is inserted into a predetermined pair of
the slots from a first end face of the stator core such that the
respective end portions of the rectangular wire elements project
from a second end face of the stator core. The rectangular wire
pieces of the sub-assembly are fixed to the end portions of the
rectangular wire elements, thereby manufacturing a stator coil
having compact coil ends easily.
Inventors: |
SEKIKAWA; Takashi;
(Kanagawa, JP) ; NISHIMURA; Kimio; (Kanagawa,
JP) ; OMATA; Masahiro; (Kanagawa, JP) ;
MATSUSHITA; Yasushi; (Kanagawa, JP) ; WU; Min;
(Kanagawa, JP) ; OHSHIMA; Takumi; (Kanagawa,
JP) ; SHIBUKAWA; Hiroaki; (Kanagawa, JP) ;
HIGAKI; Koji; (Kanagawa, JP) ; ISHIGURO;
Kunitomo; (Kanagawa, JP) ; YAMENE; Yuhei;
(Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NISSAN MOTOR CO., LTD. |
Yokohama-shi, Kanagawa |
|
JP |
|
|
Assignee: |
NISSAN MOTOR CO., LTD.
Yokohama-shi, Kanagawa
JP
|
Family ID: |
54833037 |
Appl. No.: |
15/316564 |
Filed: |
June 9, 2014 |
PCT Filed: |
June 9, 2014 |
PCT NO: |
PCT/JP2014/065276 |
371 Date: |
December 6, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 15/0081 20130101;
H02K 15/0421 20130101; H02K 15/085 20130101; H02K 3/12 20130101;
H02K 15/064 20130101 |
International
Class: |
H02K 15/085 20060101
H02K015/085; H02K 3/12 20060101 H02K003/12; H02K 15/06 20060101
H02K015/06; H02K 15/00 20060101 H02K015/00; H02K 15/04 20060101
H02K015/04 |
Claims
1. A rectangular wire stator coil manufacturing method for winding
a rectangular wire on a stator core, the stator core having a first
end face, a second end face, a plurality of teeth extending between
the first and second end faces, and a plurality of slots each of
which is formed between adjacent teeth, the method comprising:
forming in advance a plurality of rectangular wire elements by
cutting the rectangular wire to a predetermined length and bending
into a substantial U-shape; forming in advance a plurality of
rectangular wire pieces configured to connect predetermined pairs
of ends of the rectangular wire elements as a sub-assembly;
inserting each of the rectangular wire elements into each
predetermined pair of the slots of the stator core from the first
end face and causing the end portions of the rectangular wire
elements to project form the second end face; and fitting the
sub-assembly to the second end face by fixing the rectangular wire
pieces to the predetermined pairs of the end portions of the
rectangular wire elements that project from the second end
face.
2. The rectangular wire stator coil manufacturing method according
to claim 1, wherein each of the rectangular wire elements has a
bent portion bent along the first end face.
3. The rectangular wire stator coil manufacturing method according
to claim 1, wherein each of the rectangular wire pieces has a bent
portion bent along the second end face.
4. The rectangular wire stator coil manufacturing method according
to claim 3, wherein the rectangular wire pieces comprise a first
group of rectangular wire pieces each of which has a bent portion
bent radially outward along the second end face and a second group
of rectangular wire pieces each of which has a bent portion bent
radially inward along the second end face.
5. The rectangular wire stator coil manufacturing method according
to claim 1, wherein the sub-assembly is formed from the plurality
of the rectangular wire pieces and a heat conductive resin that
holds the plurality of the rectangular wire pieces in predetermined
positions.
6. The rectangular wire stator coil manufacturing method according
to claim 5, wherein the sub-assembly comprises a coolant passage
within a portion made of the heat conductive resin.
7. The rectangular wire stator coil manufacturing method according
to claim 5, wherein the sub-assembly comprises a heat radiation fin
made of the heat conductive resin.
8. The rectangular wire stator coil manufacturing method according
to claim 1, wherein the end portions of the rectangular wire
elements and the tip ends of the rectangular wire pieces are both
formed into a convergent shape toward a leading end.
9. The rectangular wire stator coil manufacturing method according
to claim 1, wherein one of an end portion of the rectangular wire
element and a tip end of the rectangular wire piece has a cutout to
accept another of the end portion and the tip end.
10. The rectangular wire stator coil manufacturing method according
to claim 1, wherein fixing the rectangular wire pieces to the
predetermined pairs of the end portions of the rectangular wire
elements includes binding an end portion of the rectangular wire
element and a tip end of the rectangular wire piece together by a
binding member.
Description
TECHNICAL FIELD
[0001] This invention relates to a method of manufacturing a
rectangular wire stator coil used in an electric motor or the
like.
BACKGROUND ART
[0002] A stator coil of an electric motor or the like is wound
around a cylindrical stator core. A plurality of teeth is provided
at equal angular intervals on an inner periphery of the stator
core. Slots are formed respectively between adjacent teeth. A wire
forming the coil is wound around the teeth through a pair of slots
formed on either side of one or a plurality of teeth.
[0003] A coil end of the wire wound around the teeth projects in an
axial direction from an end face of the stator core between the
pair of slots. When the wire is wound across a plurality of teeth
rather than a single tooth, or in other words when an extra slot
exists between the pair of slots through which the wire is passed,
the coil crosses a coil passed through the extra slot in a motor
axis direction. The coils cross at the coil ends. The number of
crossed portions differs according to the pitch of the coil
windings, or in other words the number of teeth across which the
coils are wound, such that the number of crossed portions increases
in accordance with the pitch of the windings.
[0004] When the coil ends are crossed, a length by which the coil
ends project in the axial direction from an end face of the stator
core increases, and to suppress the length by which the coil ends
project in the axial direction, lead wires of the crossed coil ends
are conventionally woven into a mesh form, for example.
[0005] With this method, the wires forming the coils are woven one
at a time, leading to an inevitable increase in the complexity of a
coil winding operation. To facilitate the winding operation,
JP2010-166803A, published by the Japan Patent Office in 2010,
proposes winding the coils by fitting a wire assembly, which is
formed by gathering together a plurality of wires in a coil shape,
into a pair of slots, and forming an axial direction step in
advance on a coil end of the wire assembly by providing a crank
portion on the coil end.
[0006] In this conventional technique, coil ends can be crossed
easily by passing a lead wire assembly of an adjacent coil through
a space formed between the coil and the end face of the stator core
by the step provided on the coil end.
SUMMARY OF INVENTION
[0007] Likewise with this conventional technique, however, the
length by which the coil ends project in the axial direction
inevitably increases as the number of crossed portions between
coils, or in other words the pitch of the windings, increases.
[0008] Moreover, although the crossed portions can be processed
more easily by forming the step, the operation to wind the
pre-formed wires around the teeth of the stator core remains
burdensome.
[0009] It is therefore an object of this invention to suppress an
increase in the length by which a coil end of a stator coil winding
projects in an axial direction, and to reduce a number of man-hours
required for a coil winding operation.
[0010] In order to achieve the above object this invention is
directed to a rectangular wire stator coil manufacturing method for
winding a rectangular wire on a stator core. The stator core has a
first end face, a second end face, a plurality of teeth extending
between the first end face and the second end face, and a plurality
of slots each of which is formed between adjacent teeth.
[0011] The method comprises forming in advance a plurality of
rectangular wire elements by cutting the rectangular wire to a
predetermined length and bending into a substantial U-shape,
forming in advance a plurality of rectangular wire pieces
configured to connect predetermined pairs of ends of the
rectangular wire elements as a sub-assembly, inserting each of the
rectangular wire elements into each predetermined pair of the slots
of the stator core from the first end face and causing the end
portions of the rectangular wire elements to project form the
second end face, and fitting the sub-assembly to the second end
face by fixing the rectangular wire pieces to the predetermined
pairs of the end portions of the rectangular wire elements that
project from the second end face.
[0012] The details as well as other features and advantages of this
invention are set forth in the remainder of the specification and
are shown in the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIGS. 1A and 1B are respectively a perspective view of a
stator coil manufactured by a rectangular wire stator coil
manufacturing method according to a first embodiment of this
invention, and an enlarged perspective view of main parts
thereof.
[0014] FIG. 2 is a cross-sectional view of main parts of a
rectangular wire stator coil.
[0015] FIG. 3 is a side view of main parts of a rectangular wire
element and a rectangular wire piece forming the rectangular wire
stator coil, as seen from a center of a stator core.
[0016] FIG. 4 is a front view of main parts of the rectangular wire
element and the rectangular wire piece as seen from an axial
direction of the stator core.
[0017] FIG. 5 is a perspective view of an outer side rectangular
wire element.
[0018] FIG. 6 is a side view of main parts of a single row of
rectangular wire elements inserted into the stator core, as seen
from the center of the stator core.
[0019] FIG. 7 is a front view of main parts of a single row of
rectangular wire elements inserted into the stator core, as seen
from the axial direction of the stator core.
[0020] FIG. 8 is a perspective view of an inner side rectangular
wire element.
[0021] FIG. 9 is a perspective view of an inner side rectangular
wire unit formed by assembling two rows of inner side rectangular
wire elements.
[0022] FIG. 10 is a perspective view of an outer side rectangular
wire unit formed by assembling two rows of outer side rectangular
wire elements.
[0023] FIG. 11 is a perspective view of a rectangular wire unit
formed by combining the inner side rectangular wire unit and the
outer side rectangular wire unit.
[0024] FIG. 12 is a perspective view of the stator core.
[0025] FIG. 13 is a perspective view of the outer side rectangular
wire unit inserted into the stator core.
[0026] FIG. 14 is a perspective view of a sub-assembly constituted
by a plurality of rectangular wire pieces.
[0027] FIG. 15 is a perspective view of the rectangular wire
element and the rectangular wire piece joined together.
[0028] FIG. 16 is a plan view of a connecting portion between the
rectangular wire element and the rectangular wire piece.
[0029] FIGS. 17A and 17B are perspective views of a connecting
portion between a rectangular wire element and a rectangular wire
piece according to a second embodiment of this invention.
[0030] FIGS. 18A and 18B are perspective views of a connecting
portion between a rectangular wire element and a rectangular wire
piece according to a third embodiment of this invention.
[0031] FIGS. 19A and 19B are perspective views of a connecting
portion between a rectangular wire element and a rectangular wire
piece according to a fourth embodiment of this invention.
[0032] FIGS. 20A-20C are perspective views of the connecting
portion between the rectangular wire element and the rectangular
wire piece, illustrating variation in the tip end shapes of the
rectangular wire element in the rectangular wire piece.
[0033] FIGS. 21A-21C are perspective views of the connecting
portion between the rectangular wire element and the rectangular
wire piece, illustrating a positional relationship to a joint
portion.
[0034] FIGS. 22A-22C are perspective views of two connecting
portions between adjacent rectangular wire elements and rectangular
wire pieces, illustrating an arrangement of an insulating
member.
[0035] FIG. 23 is a side view of the stator core and the
sub-assembly, illustrating an arrangement of a coolant passage.
[0036] FIG. 24 is a side view of the stator core and the
sub-assembly, illustrating an arrangement of a heat radiation
fin.
[0037] FIG. 25 is a longitudinal sectional view of main parts of
the sub-assembly, illustrating variation in the shape of a gap
formed in the sub-assembly.
DESCRIPTION OF EMBODIMENTS
[0038] Referring to FIGS. 1A and 1B, FIGS. 2-7, and FIG. 12 of the
drawings, a basic structure of a rectangular wire stator coil to
which this invention is applied will now be described.
[0039] Referring to FIGS. 1A and 1B, a stator 1 used in an electric
motor or the like includes a plurality of groups of coils 3 formed
by winding rectangular wire 6 on a cylindrical stator core 2. The
rectangular wire 6 is constituted by a lead wire formed by coating
an outer periphery of copper wire with an insulating material.
[0040] Referring to FIG. 12, the stator core 2 includes a first end
face 2A and a second end face 2B oriented in an axial direction.
Teeth 4 are formed at equal angular intervals on an inner periphery
of the stator core 2. Slots 5 into which the rectangular wire 6 is
inserted are formed between the teeth 4. The slots 5 open
respectively onto the inner peripheral surface of the stator core
2, the first end face 2A, and the second end face 2B.
[0041] Referring to FIG. 2, each coil 3 is formed by winding the
rectangular wire 6 four times through a pair of slots 5 straddling
five of the teeth 4, as shown by shading in the figure. The
rectangular wire 6 is wound thus through all of the pairs of slots
5 straddling five of the teeth 4. In the following description, the
plurality of groups of coils 3 mounted on the stator core 2 will be
referred to together as a stator coil.
[0042] Referring to FIG. 3, the rectangular wire 6 forming each
coil 3 is constituted by a rectangular wire element 6A that passes
through a predetermined pair of the slots 5 in the stator core 2
from the first end face 2A toward the second end face 2B, and a
rectangular wire piece 6B fixed to end portions of the rectangular
wire element 6A projecting axially outward from the second end face
2B.
[0043] Referring to FIG. 5, the rectangular wire element 6A is
formed by cutting the rectangular wire 6 to a predetermined
dimension in advance, and bending the cut rectangular wire 6 into a
substantial U-shape using a bending device or the like. A site
corresponding to a bottom portion of the U-shape is bent to a
substantial right angle. When the rectangular wire element 6A is
passed through the stator core 2, a bent portion 61 thus formed is
parallel to the first end face 2A.
[0044] Referring back to FIG. 3, the rectangular wire element 6A is
inserted into a predetermined pair of the slots 5 from the first
end face 2A. As described above, the rectangular wire 6 is wound
four times through each pair of slots 5, and therefore four
rectangular wire elements 6A are inserted into each pair of slots
5.
[0045] Referring to FIGS. 6 and 7, on the first end face 2A, the
bent portion 61 of the rectangular wire element 6A overlaps the
bent portion 61 of another rectangular wire element 6A in a motor
axis direction. To facilitate overlapping, a step 62 is formed in
the bent portion 61. It should be noted that FIGS. 6 and 7 show
only one row of rectangular wire elements 6A arranged in a
circumferential direction on an outermost peripheral side, whereas
in actuality, four rectangular wire elements 6A are disposed in
each pair of slots 5 so as to overlap in a radial direction.
[0046] Referring to FIG. 4, the rectangular wire piece 6B is fixed
to the rectangular wire element 6A passed through the slots 5 in
the stator core 2 such that the respective end portions thereof
project in the axial direction from the end face 2B.
[0047] The rectangular wire piece 6B is formed by cutting the
rectangular wire 6 to a short length. The rectangular wire piece 6B
includes a bent portion 63 that is similar to the bent portion 61
of the rectangular wire element 6A, and tip ends 64 extending in a
right angle direction from respective ends of the bent portion 63.
A similar step 62 to that of the bent portion 61 is formed in the
bent portion 63. When the bent portion 63 of the rectangular wire
piece 6B is disposed parallel to the second end face of the stator
core 2, the two tip ends 64 of the rectangular wire piece 6B are
parallel to the end portions of the rectangular wire element
6A.
[0048] The tip ends 64 of the rectangular wire piece 6B thus formed
are held such that side faces thereof contact side faces of the end
portions of the rectangular wire element 6A in the circumferential
direction, and in this condition, top faces of the respective tip
ends are joined by welding metal 20. In the following description,
the tip end 64 of the rectangular wire piece 6B and the end portion
of the rectangular wire element 6A joined at the respective top
faces thereof will be referred to as a joined pair.
[0049] It should be noted that in the figure, the rectangular wire
element 6A joined to one end of the rectangular wire piece 6B and
the rectangular wire element 6A joined to another end of the
rectangular wire piece 6B are not the same rectangular wire element
6A. In the figure, the end portion of a first rectangular wire
element 6A is joined to one end of the rectangular wire piece 6B,
and the end portion of a second rectangular wire element 6A passed
through the same slots 5 in a position adjacent to the first
rectangular wire element 6A is joined to the other end of the
rectangular wire piece 6B.
[0050] Hence, the coil 3 is formed by passing four rectangular wire
elements 6A through each pair of slots 5, and joining the
respective end portions of four rectangular wire pieces 6B to the
end portions of the four rectangular wire elements 6A projecting in
the axial direction from the end face 2A. In other words, the coil
3 is constituted by four rectangular wire elements 6A, four
rectangular wire pieces 6B, and eight joined pairs connecting the
four rectangular wire elements 6A and four rectangular wire pieces
6B.
[0051] It should be noted that a distance between the pair of slots
5 through which the rectangular wire element 6A is passed increases
toward an outer peripheral side of the stator core 2 and decreases
toward an inner peripheral side. Therefore, a width of the U-shape
of the rectangular wire element 6A is set in advance to be narrower
in the rectangular wire elements 6A disposed closer to the radial
direction inner side.
[0052] The basic structure of the coil 3 is as described above.
[0053] Next, referring to FIGS. 14-16, a rectangular wire stator
coil manufacturing method according to a first embodiment of this
invention will be described.
[0054] When the rectangular wire elements 6A and the rectangular
wire pieces 6B are connected in succession by the procedures
described above, an extremely large number of man-hours is required
to complete the stator coil.
[0055] Referring to FIG. 14, in the rectangular wire stator coil
manufacturing method according to the first embodiment of this
invention, all of the rectangular wire pieces 6B are disposed in
advance in a predetermined overlapping condition, and integrated
using resin. A sub-assembly 7 formed in this manner is then fixed
to the stator core 2, in which all of the rectangular wire elements
6A have been passed through all of the slots 5, and as a result,
the number of man-hours required to manufacture the stator coil can
be reduced.
[0056] Referring to FIGS. 15 and 16, in this embodiment, the
rectangular wire piece 6B is disposed in a predetermined position
in advance so that the tip end 64 of the rectangular wire piece 6B
and the end portion of the rectangular wire element 6A that
projects in the axial direction from the second end face 2B of the
stator core 2 are arranged side by side in the circumferential
direction, and then the rectangular wire piece 6B is molded using
resin. In this embodiment, the rectangular wire pieces 6B on the
two rows on the outer side are bent in an outward direction, and
the rectangular wire pieces 6B on the two rows on the inner side
are bent in an inward direction. By bending the outer side
rectangular wire pieces 6B in a different direction to the inner
side rectangular wire pieces 6B in this manner, the number of times
the rectangular wire pieces 6B are overlapped in the motor axis
direction can be reduced. As a result, the length by which the coil
ends of the coil 3 project in the axial direction from the second
end face 2B can be further reduced.
[0057] A heat conductive resin is preferably used as the resin.
Gaps 21 are formed in the resin to allow the end portions of the
rectangular wire elements 6A to penetrate between the tip ends 64
of the rectangular wire pieces 6B that are adjacent thereto in the
circumferential direction. More specifically, the rectangular wire
pieces 6B formed into a predetermined shape are disposed inside a
mold in a predetermined overlapped condition such as that shown in
FIG. 14, cores for forming the gaps 21 are also disposed therein,
and then the resin is poured into the mold. As a result, the
rectangular wire pieces 6B are fixed to each other in predetermined
positions by the resin. Further, by removing the cores after the
resin has hardened, the gaps 21 are formed to allow the end
portions of the rectangular wire elements 6A to penetrate between
the tip ends 64 of the rectangular wire pieces 6B that are bent
outward in the axial direction.
[0058] The sub-assembly 7 formed in this manner is fitted to the
stator core 2, in which all of the rectangular wire elements 6A
have been passed through the slots 5. At this time, the end
portions of the rectangular wire elements 6A projecting in the
axial direction from the second end face 2B of the stator core 2
are inserted respectively into the gaps 21 in the sub-assembly
7.
[0059] Referring back to FIGS. 15 and 16, when the end portions of
the rectangular wire elements 6A are inserted into the gaps 21 in
the sub-assembly 7, the end portions project so as to be arranged
side by side with the tip ends 64 of the rectangular wire pieces 6B
in the circumferential direction. In this condition, as shown in
FIG. 16, the top face of the end portion of the rectangular wire
element 6A and the top face of the tip end 64 of the rectangular
wire piece 6B are joined to each other fixedly. More specifically,
the welding metal 20 is welded thereto from above so as to straddle
the two top faces. The joining operations that are performed
between the adjacent rectangular wire elements 6A and rectangular
wire pieces 6B may be implemented in parallel simultaneously using
a dedicated joining machine, for example, such as a laser welder, a
brazing machine, or the like, for example. In so doing, the number
of man-hours required for the operation to wind the coils 3 can be
greatly reduced. The rectangular wire elements 6A are joined
closely to the tip ends 64 of the rectangular wire pieces 6B, and
therefore, as shown in FIG. 16, a gap is formed between the
rectangular wire element 6A and the tip end 64 of another
rectangular wire piece 6B located on the opposite side. This gap is
desirable since it prevents electric short circuits from occurring
between adjacent windings.
[0060] As shown in FIGS. 1A and 1B, as a result of the joining
operations, all of the coils 3 are wound.
[0061] To reduce the number of man-hours required for the operation
to wind the coils 3, the rectangular wire elements 6A can be
assembled in advance into a unit such as that described below and
inserted into the stator core 2 altogether in the form of the unit.
As a result, an operation to manufacture the stator 1 can be
performed more easily.
[0062] Referring to FIG. 9, the two inner side windings of the
rectangular wire element 6A wound four times so as to overlap in
the radial direction within the slot 5 are assembled into an inner
side rectangular wire unit 11 using the rectangular wire element
6A.
[0063] Referring to FIG. 10, the two outer side windings are
assembled into an outer side rectangular wire unit 12 using the
rectangular wire element 6A shown in FIG. 5.
[0064] The overlapping bent portions 61 of the assembled inner side
rectangular wire unit 11 and outer side rectangular wire unit 12
are fixed by resin so that the inner side rectangular wire unit 11
and outer side rectangular wire unit 12 can support themselves.
[0065] Referring to FIG. 11, the inner side rectangular wire unit
11 thus assembled is inserted from the axial direction into the
inner side of the outer side rectangular wire unit 12, whereby the
four rows of rectangular wire elements 6A are all assembled into a
single rectangular wire unit. The rectangular wire unit is then
inserted in a single operation into the slots 5 in the stator core
2.
[0066] Referring to FIG. 13, in another method, the outer side
rectangular wire unit 12 alone may be inserted into the slots 5
first, whereupon the inner side rectangular wire unit 11 is
inserted into the slots 5 on the inner side of the outer side
rectangular wire unit 12.
[0067] By likewise forming the rectangular wire elements 6A into a
unit in this manner, the number of man-hours required for the
operation to manufacture the stator coil can be reduced even
further.
[0068] The bent portions 61 of the rectangular wire elements 6A are
preferably bent in opposite directions in the inner side
rectangular wire unit 11 and the outer side rectangular wire unit
12. More specifically, the bent portions 61 of the inner side
rectangular wire unit 11 are bent radially inward, and the bent
portions 61 the outer side rectangular wire unit 12 are bent
radially outward. By bending the bent portions 61 of the inner side
rectangular wire unit 11 and the outer side rectangular wire unit
12 in opposite directions in this manner, the bent portions 61 of
the inner side rectangular wire unit 11 and the bent portions 61 of
the outer side rectangular wire unit 12 no longer overlap in the
motor axis direction, and therefore the length by which the coil
ends formed by the rectangular wire elements 6A project in the
axial direction can be reduced even further.
[0069] As described above, with the rectangular wire stator coil
manufacturing method according to the first embodiment of this
invention, the plurality of rectangular wire pieces 6B are
integrated into the sub-assembly 7 in advance, and therefore the
number of man-hours required to wind the coils 3 can be reduced.
Further, the length by which the coil ends on one side of the
stator coil project in the axial direction is reduced by forming
the bent portions 63 on the rectangular wire pieces 6B, and the
length by which the coil ends on the other side of the stator coil
project in the axial direction is reduced by forming the bent
portions 61 on the rectangular wire elements 6A.
[0070] Furthermore, by forming the bent portions 63 of the
rectangular wire pieces 6B from bent portions that bend both
outward and inward relative to the radial direction, the number of
times the bent portions 63 overlap can be reduced.
[0071] Moreover, by employing a heat conductive resin in the
sub-assembly 7, a heat dissipation property of the coil 3 can be
improved.
[0072] Next, other embodiments of this invention relating to
methods of connecting the rectangular wire element 6A to the
rectangular wire piece 6B will be described.
[0073] Referring to FIGS. 17A and 17B, a method of connecting the
rectangular wire element 6A and the rectangular wire piece 6B
according to a second embodiment of this invention will be
described.
[0074] In this embodiment, a cutout 65 is formed in advance in the
end portion of the rectangular wire element 6A. Then, before
joining the end portion of the rectangular wire element 6A to the
tip end 64 of the rectangular wire piece 6B, the tip end 64 of the
rectangular wire piece 6B is engaged with the cutout 65, and in
this condition, the end portion of the rectangular wire element 6A
and the tip end 64 of the rectangular wire piece 6B are fixed by a
binding member 66 constituted by an electric insulating material.
As shown in FIG. 16, with the end portion of the rectangular wire
element 6A and the tip end 64 of the rectangular wire piece 6B
bound integrally in this manner, the top face of the end portion of
the rectangular wire element 6A and the top face of the tip end 64
of the rectangular wire piece 6B are joined using the welding metal
20.
[0075] According to this embodiment, the end portion of the
rectangular wire element 6A and the tip end 64 of the rectangular
wire piece 6B can be joined even more closely. As a result, a
larger gap can be secured between the tip end 64 of the rectangular
wire piece 6B bound by the binding member 66 and the tip end of
another rectangular wire element 6A bound by a different binding
member 66 that is adjacent thereto in the circumferential
direction. As a result, electric short circuits between adjacent
windings of the coils 3 can be prevented even more reliably.
[0076] The binding member 66 may be constituted by a tape-form
member that is wound around the end portion of the rectangular wire
element 6A and the tip end 64 of the rectangular wire piece 6B, or
by a rigid member that fixes the end portion of the rectangular
wire element 6A and the tip end 64 of the rectangular wire piece 6B
to each other by caulking.
[0077] Referring to FIGS. 18A and 18B, a method of joining the
rectangular wire element 6A and the rectangular wire piece 6B
according to a third embodiment of this invention will be
described.
[0078] In this embodiment, copper wire exposed portions 66 and 67
are formed in advance by cutting away the insulating material in
the shape of a strip from a part of the end portion of the
rectangular wire element 6A and a part of the tip end 64 of the
rectangular wire piece 6B. The exposed portions 66 and 67 are then
placed adjacent to each other, and in this condition, the end
portion of the rectangular wire element 6A and the tip end 64 of
the rectangular wire piece 6B are fixed to each other by a binding
member 68 constituted by a conductive material. As shown in FIG.
16, with the end portion of the rectangular wire element 6A and the
tip end 64 of the rectangular wire piece 6B bound integrally in
this manner, the top face of the end portion of the rectangular
wire element 6A and the top face of the tip end 64 of the
rectangular wire piece 6B are joined using the welding metal
20.
[0079] According to this embodiment, it is possible to secure a
perfect electrical connection between the rectangular wire element
6A and the rectangular wire piece 6B. Meanwhile, the binding member
68 binds the tip end 64 of the rectangular wire piece 6B closely to
the end portion of the rectangular wire element 6A, and therefore a
gap can be secured between adjacent joined pairs in the
circumferential direction, or in other words adjacent windings in
the circumferential direction. As a result, electric short circuits
between the windings of the coil 3 can be prevented. It should be
noted that in order to prevent electric short circuits between the
windings completely, the binding member 68 is preferably formed
with a laminated structure in which a surface of the binding member
68 that contacts the exposed portions 66 and 67 is formed from a
conductive material and a surface of the binding member 68 that is
exposed to the outside is constituted by an insulating
material.
[0080] Referring to FIGS. 19A and 19B, a method of joining the
rectangular wire element 6A and the rectangular wire piece 6B
according to a fourth embodiment of this invention will be
described.
[0081] In this embodiment, small cutouts 69 are formed in advance
respectively in the end portion of the rectangular wire element 6A
and the tip end 64 of the rectangular wire piece 6B. The cutouts 69
are not formed in mutually contacting parts of the end portion of
the rectangular wire element 6A and the tip end 64 of the
rectangular wire piece 6B.
[0082] With the end portion of the rectangular wire element 6A and
the tip end 64 of the rectangular wire piece 6B in contact with
each other, the end portion of the rectangular wire element 6A and
the tip end 64 of the rectangular wire piece 6B, the respective
cross-sections of which having been reduced by the cutouts 69, are
fixed by a binding member 70 constituted by an electric insulating
material. With the end portion of the rectangular wire element 6A
and the tip end 64 of the rectangular wire piece 6B bound
integrally in this manner, the top face of the end portion of the
rectangular wire element 6A and the top face of the tip end 64 of
the rectangular wire piece 6B are joined using the welding metal
20.
[0083] Likewise according to this embodiment, the end portion of
the rectangular wire element 6A and the tip end 64 of the
rectangular wire piece 6B are joined to each other closely so that
a gap is secured between adjacent windings, and therefore electric
short circuits can be prevented from occurring between the windings
of the coils 3. Further, the binding member 70 can be used in a
smaller amount than in the second and third embodiments. Moreover,
the binding member 70 binds the rectangular wire element 6A and the
rectangular wire piece 6B further toward the tip end side than in
the second and third embodiments, and therefore the binding member
70 can be applied more easily.
[0084] Referring to FIGS. 20A-20C, variation in the shapes of the
end portion of the rectangular wire element 6A and the tip end 64
of the rectangular wire piece 6B will be described.
[0085] Similarly to the fourth embodiment, the small cutouts 69 are
formed in advance in the end portion of the rectangular wire
element 6A and the tip end 64 of the rectangular wire piece 6B
shown in FIG. 20A. Regardless of whether or not the binding member
70 is applied, this tip end shape is favorable in terms of securing
sufficient space for disposing members and securing a heat
dissipation property.
[0086] In FIG. 20B, tapered portions 70 are formed on a part of the
end portion of the rectangular wire element 6A and the tip end 64
of the rectangular wire piece 6B instead of the cutouts 69.
Likewise with the tapered portions 70, similar favorable effects to
those of the cutouts 69 are obtained in terms of securing
sufficient space for disposing members and securing a heat
dissipation property.
[0087] In FIG. 20C, conical portions 71 are formed on a part of the
end portion of the rectangular wire element 6A and the tip end 64
of the rectangular wire piece 6B instead of the cutouts 69.
Likewise with the conical portions 71, similar favorable effects to
those of the cutouts 69 are obtained in terms of securing
sufficient space for disposing members and securing a heat
dissipation property.
[0088] These tip ends are pointed. Even when pointed tip ends are
employed, flat top faces 72 are still secured respectively on the
end portion of the rectangular wire element 6A and the tip end 64
of the rectangular wire piece 6B. As shown in FIGS. 21A-21C, the
end portion of the rectangular wire element 6A and the tip end 64
of the rectangular wire piece 6B are joined at the remaining top
faces 72 using the welding metal 20.
[0089] Further, as shown in FIGS. 22A-22C, by interposing an
insulating member 73 between the small cutout 69, tapered portion
70, or conical portion 71 described above and the small cutout 69,
tapered portion 70, or conical portion 71 of the winding that is
adjacent thereto in the circumferential direction, a gap can be
secured between adjacent windings.
[0090] Referring to FIG. 23, a coolant passage 75 may be formed in
advance in the resin part of the sub-assembly 7. By circulating a
coolant through the coolant passage 75, the stator 1 can be cooled
while operative.
[0091] Referring to FIG. 24, to promote cooling of the stator 1
when the stator 1 is operative, heat radiation fins 76 are
preferably formed on the sub-assembly 7 so as to be oriented
axially outward.
[0092] Referring to FIG. 25, when the gap 21 is formed in the
sub-assembly 7, a diameter of the gap 21 may be narrowed gradually
toward the axial direction outer side. Here, the axial direction
outer side corresponds to the upper side of FIG. 3 and FIG. 24. In
FIG. 25, the end portion of the rectangular wire element 6A
penetrates the gap 21 upwardly from below. By narrowing the
diameter of the gap 21 upwardly in this manner, the gap 21 itself
functions as a guide for guiding the end portion of the rectangular
wire element 6A. As a result, the end portion of the rectangular
wire element 6A, which projects toward the axial direction outer
side from the gap 21, can be positioned accurately.
[0093] Although the invention has been described above with
reference to certain embodiments, the invention is not limited to
the embodiments described above. Modifications and variations of
the embodiments described above will occur to those skilled in the
art, within the scope of the claims.
INDUSTRIAL APPLICABILITY
[0094] As described above, with this invention, an increase in the
length by which a coil end of a stator coil projects in an axial
direction is suppressed, and a number of man-hours required for an
operation to wind a coil onto a stator core is reduced. Therefore,
this invention brings about favorable effects in terms of size
reduction and production rationalization in an electric motor for a
vehicle, for example.
[0095] The embodiments of this invention in which an exclusive
property or privilege is claimed are defined as follows:
* * * * *